OUT WITH THE NÜ Metal, in all its spread-winged glory, is now enjoying an unlikely wide acceptance — and Mastodon are one of the genre’s most successful tall-tale tellers.

When you get down to it, most music is an attempt to create auditory allegories for our life experiences, whether they’re joyous Maypole dervishes or nightmarish St. Vitus’ dances of doom. As a subgenre of rock and roll, heavy metal leans in the latter direction, and in its nearly four decades of existence, it’s managed to create its very own idioms. Favoring instrumental mastery and dark themes writ large across well-worn jean jackets, metal has always risked ridicule from other rock forms in its unbending desire to remain true to its ideals of chaos and tribal loyalty.

But what is it that makes a certain band or song or album or riff “metal”? Lyrical themes? The timbre of the vocals and guitars? Is there a set of rules for how the instruments should interact? Is there some sort of semiotic checklist?

“Naw, it’s just music that’s really fucking brutal.” The voice on the other end of the line belongs to an individual who enjoys some authority when it comes to defining metal. In addition to having affixed “brutal” to “metal” for 13 years with knuckle-dragging sludge Neanderthals High on Fire, Matt Pike also manned the low-tuned guitar in doom pioneers Sleep — a power trio who played a major part in rescuing heavy music from the alt-friendly ’90s’ aversion to long flowing locks and brutal palm-muted riffage. He refines his definition of metal by citing his band’s forthcoming long-player, Snakes of the Divine: “It’s just, you know, hit-you-in-the-face stuff — just heavy and shit.”

Pike and company are currently hitting throngs of young uns in their collective faces as part of a tour that joins High on Fire with fellow down-tuners Mastodon, spazzcore local heavies Converge, and, to top it off, Dethklok — yes, as in the fictitious metal band from the Adult Swim cartoon Metalocalypse. Somehow, this tour, which comes to the House of Blues Tuesday and Wednesday, makes total sense: all three bands not only specialize in face-melting riff runs but are also merchants of metal’s continuously over-the-top allegorical æsthetic — even if the headliners amount to a pit band with animated corollaries projected on a screen that covers the stage.

Mastodon are arguably one of the most successful metal tall-tale tellers of all time. Their first major success came in 2004 with Leviathan, a loose concept based on Moby-Dick. This past spring they hit the Billboard Top 20 with Crack the Skye (Reprise), a dense song cycle revolving around Rasputin, astral travel, and Steven Hawking’s theories on wormholes.

“Our stuff, it’s all personal, you know, but it’s masked in this whole other story,” explains Mastodon drummer extraordinaire Brann Dailor. “We don’t want to be super-literal, because if we did, the audience would be like, ‘Oh, that is just something that happened to him.’ So it’s way better to create a new story with urban legends, Zoroastrian stuff, shit like that. Plus, it’s all great content for awesome metal T-shirts!”

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